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    <script>

        // resolve 快速的创建一个promise成功的实例
        const p = Promise.resolve(4) ;

        p.then(res => {
            console.log(res);
        })


        // resolve 快速的创建一个promise实例的实例
        const p2 = Promise.reject('err') ;
        p2.then(res => {
            console.log(res);
        }).catch(err => {
            console.log(err);
        }) 

    </script>
    
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